This invention relates to a caramel-containing cellulosic article and a method for manufacturing this article.
Generally, it is known that for certain food products enclosed in cellulosic food casings, it is desirable to impart color to the casing and/or color and flavor to the encased food during the elevated temperature processing to cook the food.
Caramel has been proposed to impart brown color to the casing and/or the food. Caramel is a brown to black liquid or solid having the characteristic odor of burnt sugar and a pleasant, bitter taste. At normal usage levels it has little or no taste, however. Caramel is prepared by the controlled heat treatment of the following food-grade carbohydrates: dextrose, invert sugar, lactose, malt syrup, molasses, starch hydrolysates and fractions thereof, and sucrose. Various food-grade acids, alkalies, and salts may be used to assist caramelization. From the physical standpoint, caramel consists essentially of colloidial aggregates which are soluble in water but only partly soluble in alcohol-water solutions.
Caramel has also been proposed as a cross-linking agent in the production of collagen casing. U.S. Pat. No. 3,860,728 discloses that the carbonyl functional groups facilitate cross-linking by reacting with the collagen, becoming part of the protein matrix. This is said to enhance the strength and performance of the collagen.
U.S. Pat. No. 4,038,438 discloses impregnation of regenerated cellulose and collagen gel stock casings with caramel solutions. The caramel is then insolubilized by cross-linking. To promote the cross-linking in cellulose, a cationic thermosetting resin is used to cross-link the caramel into the cellulose to produce a nonextractable colored casing.
Canadian Pat. No. 713,510 teaches that for coloring, a caramel coating may be applied to the interior surface of a cellulose casing stick, as for example by slugging the casing interior with a caramel-containing solution. This coating is then transferred to the encased food during the high temperature processing step. A uniform transfer of caramel to the encased food is apparently not contemplated by the patentee because the irregularities of the interior surface of the shirred stick would certainly prevent achieving a uniform coating.
Chiu U.S. Pat. No. 4,219,574 describes a cellulosic food casing in which caramel and an antiblock agent are impregnated in at least one of the interior and exterior surfaces of the casing.
A problem with the aforementioned caramel-impregnated cellulosic article is that the caramel is extractable in water and steam so that when encased food is processed at elevated temperatures in a controlled humidity atmosphere, the caramel is solubilized, extracted from the casing and transferred to the food product. For certain food products this is commercially nonacceptable. For certain products, it is essential that the casing retain its dark brown caramel color. As used herein, "steam" refers to the controlled humidity-elevated temperature conditions commonly used for thermally processing food products.
Still another limitation of caramel-impregnated articles in the form of food casings is that they may not be soaked in water prior to stuffing. Presoaking is commonly practiced and would result in leaching out of the caramel.
For certain food products, it is desired to impart smoke color and flavor to the food product in the food casing. This may be accomplished using vapor derived from controlled oxidation of wood in a smoke house, or by transferring the active color and flavor ingredients from a liquid smoke impregnated casing during the food processing step. These ingredients react with proteins in the food surface by way of the well-known Browning reaction to impart a brown color to the food outer surface. The liquid smoke is also derived from the controlled oxidation of wood to produce vapors which are condensed in water. In some instances, the tar remaining in the condensed liquid smoke is depleted before treatment of the casing. For example, U.S. Pat. No. 4,500,576 teaches that the tar may be depleted by extraction in a solvent such as methylene chloride. Alternatively, the tars may be removed by partial neutralization with a base, preferably in a controlled low temperature range. In other instances, for example with fiber reinforced cellulose casing as described in U.S. Pat. No. 4,377,187, the tars are not removed from the liquid smoke before impregnation.
A limitation of this acidic liquid smoke impregnation approach is that certain customers prefer a darker brown food casing color after thermal processing than can be achieved with low pH liquid smoke or even partially neutralized liquid smoke.
Another method of imparting smoke color and flavor to the encased food is by the use of alkalized liquid smoke in the manner described in U.S. Pat. Nos. 4,442,868 and 4,446,167. The precipitated tars during partial neutralization are resolubilized by the addition of further base to raise the liquid smoke pH to at least 10. The resolubilized tar-containing liquid smoke is then contacted with a surface of the cellulosic casing for impregnation thereof. A relatively dark final casing color results from treatment by such alkalized liquid smoke. However, use of alkalized liquid smoke also creates several additional problems when compared with non-alkalized liquid smokes. These include an undesirable casing odor, non-uniform appearance of the liquid smoke-impregnated casing, and residual tars. Also, when this alkaline smoke treated casing is peeled from the processed food such as meat, the ends of the food product are unacceptably dark and non-uniform. This is because there is more casing per unit area of food surface at the ends, due to wrinkles and gathering of casing.
Still another possible approach to providing the desired dark brown casing color is to introduce one or more pigments by introduction during the casing extrusion step. This does produce a darker casing, but the final casing color on the food product is often rather opaque or nontransparent. In addition, it is difficult to match a natural dark brown color with a combination of pigments.